There are many obvious films that flash in the brain while watching “Inherent Vice.” It’s “The Big Sleep,” another film where the impenetrability of the plot in no way lessens the entertainment of each and every scene. It’s “The Big Lebowski,” with a perpetually toking lead — here, Joaquin Phoenix’s wild-haired, mutton chopped Larry “Doc” Sportello. Being a film by Paul Thomas Anderson, it boasts bits of his onetime employer, Robert Altman, including “The Long Goodbye,” which dumped a mumbly Philip Marlowe into pot-hazed and boob-sprinkled 1973. The humor, though, is closer to “Brewster McCloud”: zany, wacky, almost alienatingly eccentric.

“Inherent Vice” is all of these films and more. And yet — like Anderson’s “The Master,” as well as “Punch-Drunk Love” — there’s nothing remotely like it. Actually, there is: It’s a lot like “Inherent Vice,” the Thomas Pynchon novel on which it’s based. It’s a faithful adaptation, or as faithful as one can be in 148 minutes; to write the screenplay, Anderson first transcribed the entire thing verbatim into script form, then hacked it down from phone book-size. He chucks key scenes, whittles down certain characters into one-off cameos and loses some of the better jokes. (Also gone are the songs Pynchon namechecks, though gaining Can and a Jonny Greenwood score is nothing to sneeze at.) But it plays like Pynchon: a highly digressive, absurdist alternate reality that delights in confusing anyone trying to “solve” it as pure, cold narrative. It’s just Pynchon filtered through another, almost equally oddball voice.

As with the book, you don’t need to know what’s going on at any point — or even be able to coherently synopsize the foundation of the plot — to get a ton out of it. But for the record, it concerns our permanently disheveled and consonant-impaired hero’s attempt to track down two AWOL figures: a real-estate mogul (Eric Roberts) and a surf rock saxophonist (Owen Wilson). The dense mystery — mysteries, actually — quickly becomes as impossible to follow as the plot of a “Pirates of the Caribbean” entry. But that doesn’t matter: Every scene is immaculately conceived and played — a series of tete-a-tetes between Doc and an all-star cast. And not being able to follow the plot grants a kind of freedom, allowing you to soak up the vivid atmosphere and dwell on the performances, wordplay and copious visual gags without needing to figure who’s doing what and/or to whom.

Every actor is game, starting with Phoenix, who isn’t a “The Dude”-style burner, but a loopy open nerve prone to leftfield freak-outs and other nonsensical bits of business. It’s a very physical performance, and Phoenix uses all of his body to keep us on edge. He’s not our guide into a bizarre world, but a grotesque surrounded by other, different kinds of grotesques. Among those is Josh Brolin’s Detective Bigfoot, a cheerfully corrupt cop with a flattop ’do, prone to loud noises and deadpan boasts like, “It’s been a long day of civil rights violations.” Some, like Martin Short and Jeannie Berlin, lean more towards very weird (very, very weird) sketch comedy. On the other side, Katherine Waterston, as one of Doc’s exes, who gets the movie’s plot gears moving, periodically swings by to slow the movie down to an intensely quiet crawl, commanding we all pay attention to her honey-dripped line readings. (Speaking of which, Joanna Newsom does some fine sing-song narration, sometimes while talking to the camera — a way to keep the novel’s other great voice, Pynchon’s, in the picture.)

The real star, though, is Anderson, who stays true to Pynchon while asserting his own, uniquely bizarre sensibility. “Inherent Vice” is debatably more of a comedy than even “Punch-Drunk Love,” which raged with Adam Sandler’s usually hidden anguish, while this, like Doc, is simply addled, if also always teetering on the edge of real violence. (That said, even the few deaths are at least faintly wacky.) Anderson’s style of comedic direction, though, is completely different. He likes to compose his shots so that actors enter at weird places, or zoom through in amusing ways. Some scenes are done in one meticulously offbeat take, while visual gags pop up on buildings or on beer cans. Some of the biggest laughs come from the way actors traverse the images, or simply from some non sequitur that’s said or shown.In many ways it's a live-action cartoon; if it's part Robert Altman, it's Altman by way of Frank Tashlin.

On first viewing at least, “Inherent Vice” doesn’t seem to have any pretentions. It’s not saying anything Important (unless it secretly is), and Anderson almost completely neuters the novel’s alterna-world reflection on 1970, with the 1960s still alive as a fading ghost. (Even just playing songs from 1972, including “Harvest”-era Neil Young, makes the film feel slightly unstuck in time.) There’s almost certainly something deeper one can read in it, but it’s a film that’s more about capturing a tone and feeling, about creating a vibe. It’s less a whodunit than a hang-out movie, where you spend time with fascinatingly abnormal characters, as well as groove on an even more peculiar sense of humor. Even if it never coalesces into something meatier on repeat visits, it’s still special.